1. Field of the Invention
The present invention relates to an apparatus for conveying particulate objects between steps to process particulate objects, e.g., particulate polycrystalline silicon, used in manufacturing spherical semiconductor devices.
2. Description of the Related Art
Hitherto, normally, to form semiconductor devices, a method of forming a circuit pattern on a silicon wafer and dicing it as required for forming chips has been adopted. In recent years, an art of forming a circuit pattern on a ball semiconductor of spherical single crystal silicon, etc., having a diameter of 1 mm or less and manufacturing semiconductor elements thereon has been proposed.
For example, a technique to form discrete elements of MOS devices, solar batteries, optical sensors, etc., or semiconductor integrated circuits by use of spherical single crystal silicon has been proposed. To form discrete devices and integrated circuits, particulate objects, e.g., polycrystalline or single crystal silicon balls, obtained by, for example, crushing an ingot into particulate objects of desired size, are subjected to various treatment steps of a grinding step, a lapping step, a mirror polishing step, a washing step, a thin film forming step, a resist application step, a photolithograpy step, an etching step, etc., and conveying steps. A heat treatment step for transforming polycrystalline silicon into single crystal silicon or amorphous silicon is sometimes used. To efficiently manufacture the spherical semiconductor elements, the treatment steps and the conveying steps need to be concatenated to form a line.
The treatment steps are executed in various atmospheres containing not only gases of active gases, inert gases, etc., but also liquids of water, solutions, etc. To efficiently manufacture and treat the spherical semiconductor elements, it is necessary to concatenate the steps of manufacturing and treating the spherical objects of spherical silicon by means of hollow, cylindrical means, e.g., pipes, and to convey the spherical objects within the cylindrical means by the utilization of a conveying force of fluid.
The inventors proposed a spherical object conveying apparatus capable of conveying spherical objects of spherical single crystal silicon, one by one.
Particulate objects of polycrystalline silicon as a starting material are not perfectly spherical and indefinite in shape. Therefore, it is difficult to convey those objects one by one. If two or larger number of the particulate objects are put in the conveying path, it is difficult to automatically convey and treat the particulate objects, and hence it is impossible to treat the particulate objects of spherical silicon within the closed space of the pipe, for example. For this reason, the spherical silicon cannot fully exhibit its advantages, and this fact greatly hinders the progress of the ball semiconductor.